1. Field of the Invention: This invention relates to apparatus and methods adapted to precondition air for human use, specifically heating and/or cooling air. More specifically, this invention is directed to an apparatus and apparatus for preconditioning air for use in the cabins of parked aircraft.
2. State of the Art: In flight, passenger aircraft rely on on-board systems to provide preconditioned air for their passengers. These systems conventionally rely on the power provided by the operation of the aircraft's main engines or the auxiliary power units engine for their individual operation. Once the aircraft has landed at an airport or similar facility, there exists a continuing need to supply a quantity of preconditioned air to the aircraft, especially during passenger loading and unloading operations.
The continued operation of the aircraft's auxiliary engine in order to provide a source of power for the operation of the preconditioned air systems of parked aircraft results in several negative implications. First, the burning of aircraft fuel while the aircraft is parked on the ground for extended periods has raised environmental concerns in that such burning tends to materially raise the levels of air pollution in the environs of the aircraft. Aircraft engines are not typically fitted with air pollution devices. It follows that the operation of such engines on the ground at a fixed location, especially in an environment wherein several aircraft may be simultaneously assembled may lead to a considerable deterioration in the surrounding air quality.
Secondly, owing to the high cost of such fuels, the burning of jet fuel to provide power for preconditioning of air has been viewed as a very inefficient use of energy resources. Thirdly, the operation of the aircraft's engines for purposes of powering an air preconditioning system leads to premature aging of the engines as a result of the wear and tear which inures from such operation.
In view of the concerns outlined above, recent attention has been focused on the use of preconditioning air systems which rely on power sources other than those available on-board the aircraft. Representative efforts in providing systems which rely on ground based power supplies are those disclosed in the following U.S. Patents: U.S. Pat. No. 4,835,977 (Haglund) issued 6 Jun. 1989; U.S. Pat. No. 5,031,690 (Anderson et al) issued 16 Jul. 1991; U.S. Pat. No. 4,352,273 (Kinsell et al. issued 5 Oct. 1982); and U.S. Pat. No. 2,585,570 (Messinger et al.) issued 12 Feb. 1952 and U.S. Pat. No. 4,272,967 (White) issued 16 Jun. 1981.
While conventional systems have been suggested which utilize ground based power supplies, the continuing problem exists of adapting such systems to the requirements of different sized aircraft. Presently, there exists a multitude of aircraft models and types, each with their own respective passenger carrying capacity and cabin configuration. In large part the cooling requirements for a preconditioned air unit are determined by the number of passengers being housed within the cabin being supplied with preconditioned air, as well as the internal air distribution network and the overall spatial dimensions of the cabin. It follows that a particular precondition air system designed for servicing a given number of passengers and cabin configuration may prove inadequate for servicing an aircraft having a significantly larger passenger capacity and cabin configuration.
Presently, there does not appear to be an apparatus which can be associated with a prior existing preconditioned air system in order to enhance the cooling capacity of that preexisting preconditioned air system to increase that cooling capacity sufficiently to service an aircraft having a larger cooling requirement than that for which the initial preconditioned air system was designed.
There continues to exist a need for an apparatus adapted for enhancing the cooling capacity of a given preconditioned air system which relies on a ground based power supply.